Create StringPermutations.java

Author: SedaKunda

Hard-Level/StringPermutations.java

@@ -0,0 +1,44 @@
+/*
+Write a program which prints all the permutations of a string in alphabetical order. We consider that digits < upper case letters < lower case letters. The sorting should be performed in ascending order.
+*/
+
+import java.io.*;
+import java.util.*;
+public class Main {
+	static List<String> a = new ArrayList<String>();
+    public static void main (String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new FileReader(new File(args[0])));
+           String line;
+           while ((line = br.readLine()) != null) { 
+        	   a.clear();
+        	   Main.permute3(line); 
+        	   Collections.sort(a, new Comparator<String>() {
+					@Override
+					public int compare(String s1, String s2) {
+						return s1.compareTo(s2);
+					}
+        		});
+        	   System.out.print(a.get(0));
+        	   for (int i = 1; i < a.size(); i++) {        		   
+        		   System.out.print("," + a.get(i));
+        	   }
+        	   System.out.println();
+           }
+           br.close();
+    }
+    public static void permute3 (String s) {
+    	permute3("",s);
+    	
+    }
+    private static void permute3 (String p, String s) {
+    	if (s.length()==0) {
+    		a.add(p);
+    	}
+    	else {
+    		for (int i = 0; i < s.length(); i++) {
+    			permute3(p+s.charAt(i), s.substring(0, i) + s.substring(i+1, s.length()));
+    		}
+    	}
+
+    }
+}